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Face perception: Flashcards Preview

why is face processing important?

face processing is a crucial cognitive ability. A lot can be learned about out social world from the faces of others. Faces provide information about age, race, gender, physical health and emotional state. Thus providing good reason for us to pay special attention to faces.

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OKN

based on the fact that the eyes tend to follow or track the motion of one element at a time in a steadily moving display. As the tracked element moves out of sight, the eyes will snap back to fixate another one. This can be used as an objective measure of an infants ability to see detail in a moving stimulus.

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Visual evoked potentials

measures neural activity in response to visual stimuli. It allows you to see if the brain has identified a visual stimulus. If there is a peak in brain activity then this suggests they have registered the visual stimulus.

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Preferential looking

a technique whereby you shown infants two stimuli - one on the left and one on the right and you measure their looking to see if they have a preference for one over the other.

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Habituation

involves repeatedly presenting an infant with a given stimuli until the infant response to it habituates, that is it declines. Then a novel stimulus is presented. If the infants response increases (dishabituates) then the researcher can infer that the baby can discriminate between the old and the new stimulus.

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Goren

Shown that newborns as young as nine minutes old demonstrate preferential tracking of faces over non face stimuli. these results suggest that face processing may have a prenatal component. Thus, even before they have had any experience of the world, visual discriminations are being made.

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Simion

However, other people have argued that it is not faces that are special but infants prefer the characteristics of faces and this influences a natural bias. For example, Simion has shown that infants will look at stimuli that have the properties of faces (they are top heavy) but are not actually faces. Therefore suggesting a domain general perceptual bias – this means it is not specific to faces and it generalises across species and objects.

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eye contact?

further research has shown the bias is in fact more specific to faces, for example at 13 hours old infants appear to be sensitive to the presence of eyes and prefer to look at faces that engage them in eye contact. Establishing this mutual gaze provides the main mode of establish a communicative context between humans and allowing for joint attention. This exceptionally early sensitivity to mutual gaze demonstrates the major foundation for later development of social skills and possibly offers the position that face processing is an innate capability.

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Field - mums

Field found that infants prefer to look at their mother over a stranger at just 45 hours old. However, there is a possibility that voice cues, as well as other cues may have lead to this discrimination. For example, there are two studies that give clues as to how infants can tell if it is their mother or not. One study put the mum and the stranger in headscarves, and then there is no longer a preference for looking at the mum, this suggests that the baby is using cues such as the colour of the hair and external features to tell them that this is their mother. There is also another study that prevented the mother from previously talking to the baby and then the baby would no longer prefer to look at the mother to the stranger. This suggests that there is something about hearing the voice in the womb, and then hearing it once they are born and linking the voice to the face, and this is perhaps how they can recognise their mothers face.

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melzoff and moore?

Meltzoff and Moore found that newborn infants will imitate a variety of facial gestures they see an adult model performing. This led them to suggest that newborns being life with some grasp of people and their ability to recognise when their facial behaviour is being copied implies that there is some representation on their own bodies. However, despite the large number of reports of imitation in young infants, however, there are still researchers who would question the replicability and generality of the effect

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Field - emotion?

However in a further study by Field et al., they found support for this; that infants as young as one week are very sensitive to emotions in faces. They showed infants photographs of different emotional facial expressions and then took the image of the infants face and asked others to determine what emotional expression the infants were looking at. The observer can guess the models expression based on the infants expression.

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Brain damage?

The idea that face recognition may be innate and independent from experience is also supported by the neuropsychological finding that brain damage at one day of age can lead to a lasting visual recognition deficit that results in a profound impairment in face recognition, known as prosopagnosia.

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what is configural processing?

Face expertise refers to the ability to process and recognize faces using efficient processing styles, such as configural processingConfigural processing, a more advanced processing style than featural, refers to the perception and recognition of faces on the basis of not only the features but also the spacing between features

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what is featural processing?

Featural processing refers to the perception and recognition of faces on the basis of the individual features themselves, such as the shape of the eyes or the size of the nose.

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what is holistic processing?

refers to the perception and recognition of faces as a whole rather than based on parts of the face.

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What did Diamond and Carey find?

Diamond and Carey attempted to determine the nature of children’s immaturity in identifying faces. They found that one reason might be that they rely more on superficial external characteristics for example; 6- and 8-year-olds are influenced more by paraphernalia than are 10-year-olds and adults when matching unfamiliar faces. From this, Diamond and Carey proposed that some core features of face processing do not emerge until around 10 years of age, suggesting that young children encode faces analytically using featural information and a qualitative change occurs around 10 years of age such that older children and adults process faces configurally.

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Kelly et al.,

A method of assessing face expertise involves assessing the other-race effect. The other-race effect refers to individuals being better able to discriminate faces within their own race than within another race. As one gains experience with faces within their own race, discrimination of faces within other races diminishes. The other-race effect is considered to be evidence of developing face expertise. Kelly et al., investigated how faces observed within the visual environment affect the development of the face-processing system during the first year of life. Infants were presented with pairs of faces from different races that were matched for gender, attractiveness and distinctiveness. Newborn Caucasian infants looked at each face in the pair equally, suggesting no spontaneous preference for any of the races concerned. In contrast, three-month-old children preferred to look at faces of their own races – spending about 60% of their time looking at their own race and 40% of time looking at other race faces. By nine months of age the infants would only discriminate faces from their own racial group

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Pascallis et al.,

found that 6-month-old, but not 9-month-old human infants, were able to discriminate between two monkey faces. These findings were attributed to a perceptual narrowing phenomenon; that is, selective experiences with familiar stimuli lead to a decline in the ability to recognize other unfamiliar stimuli.

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development of face preference for mother?

Furthermore, at around 4 years, the infant will stop preferentially looking at their mother. This was measured by event related potentials. So at 18-24 months there is a greater response to the mothers face over the strangers face but at 45-54 months, this is reversed and there is a greater response to the strangers face over the mothers face. This change is brain response corresponds to a change in behaviour – for example, at around this age, children become friendlier towards strangers and are exploring their environment more.

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Sugita:

Recent monkey studies have provided intriguing information to further the debate of whether face processing is an innate process, or has an origin in a more general system that becomes specialised with experience (Sugita). Newborn monkeys were separated immediately from their mother after birth and were deprived of facial stimuli throughout a deprivation period of 6-24 months. When presented with faces, the monkeys showed strong preferences for both human and monkey faces over non-face objects, even though they were not exposed to faces of any kind. The results suggest that face detection is protected against for at least two years and is consistent with the idea that newborns are able to detect the basic relational features of the face. However, it is possible that the infant monkeys could acquire the knowledge about the relational feature of the face through the proprioceptive and tactile information, and therefore, that the face-like features might become a familiar and attractive visual object.

Sugita further demonstrated that experience also plays a crucial role in the development of face processing. After face-deprivation, the infant monkeys were exposed to either human faces or monkey faces for one month. Rather than looking at both faces equally like they had done previously– their preferences changed dramatically and after this period they preferred the type of face they had been exposed to. This effect was present a year after the monkeys were moved into a normal environment. These results present the concept of perceptual narrowing, that is, selective experiences with familiar stimuli lead to a decline in the ability to recognize other unfamiliar stimuli and indicate the existence of a sensitive period for face perception, where specific experiences gained over a short period significantly affect later development.

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Sangrigoli

Sangrigoli et al., found that three to nine year old Korean children who were adopted by Caucasian families in Europe showed an ORE but in the opposite direction to normal: these children found it harder to discriminate between Korean faces than between Caucasian faces. This further supports the argument that experience is vital in the development face processing abilities, as early experience with faces of a particular race can produce an enduring bias towards better recognition for that race. Additionally, the bias can be reversed given sufficient exposure to other races.

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goodman

Goodman et al., provide extra support for the role of experience in face processing. Results found that children who had experienced meaningful interactions with both African/Caucasian races recognized both races equally well but showed an ORE for Asian faces. Thus, although we may have an innate bias to respond to faces, experience during the first few years after birth shape our face-processing ability to support quick and accurate recognition of familiar faces.

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maltreated children?

Maltreated children often display unusual patterns in their abilities to recognize, express, and regulate emotional states. Pollack, discovered that children raised in abusive households demonstrated altered facial emotion processing. In particular, they exhibited a response bias for angry faces, they were more likely to match any emotional situation to a picture of an angry face. They also attended to angry faces more than control and had trouble disengaging from angry faces. Subsequently, the nature of an infant’s learning environment can affect their facial emotion recognition abilities and it appears that difficulty in controlling attention when processing threatening interpersonal signals may make it difficult for abused children to accurately perceive and regulate emotions in social contexts.

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cataracts?

A unique method that has been used to examine the role of early experience on face processing abilities, has been to compare individuals with normal visual experience to individuals who were born with cataracts in both eyes that were sufficiently dense enough to deprive them of all visual input until they were later removed. Le Grand et al., found that early visual experience is necessary for some, but not all, components of face processing. Several years after the treatment for cataracts, patients demonstrated normal sensitivity to first-order relations and normal processing of internal features and contour. However, visual deprivation during the first few months of life prevents the later development of normal holistic processing and second-order relations. Thus early visual experience is necessary to set up (or maintain) the neural architecture that allows the development of normal holistic processing and further supports the notion of a sensitive period in face processing.

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morton and johnson

Morton and Johnson proposed the CONSPEC model that suggested that faces are special to newborns because of the existence of an innate face-detecting devise (CONSPEC), which selectively responds to the unique structure of a face, as defined by the correct location of internal facial features. This mechanism orients a newborn’s gaze toward any face-like pattern that may appear in their visual field, thus allowing for the development of specific cortical circuits for the processing of faces (CONLERN). With repeated exposure to faces, the CONLERN system rapidly develops into expert system. Thus, innate orientating mechanisms are responsible for the initial face following in neonates that are possibly implemented by sub-cortical structures, however, repeated exposure to faces allows for finer face encoding and thus better face processing. Therefore, infant’s knowledge of faces may not be innate, but there is an innate bias that is not dependent on experience, to fixating and following a face that in turn allows them to learn about that stimulus.

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perceptual narrowing

Werker and Kuhl tested the ability of infants of different ages to discriminate speech sounds. The infants were all from English speaking homes and were tested with speech contrasts that are not used in English but are important in two other languages. The babies learnt that whenever they heard a change in the series of sounds they were listening to they could see an interesting sight by turning their head to one side. Thus, discrimination between the speech sounds was inferred if the infants quickly turned their heads in the correct direction following a sound change. By 6-8 months of age infants readily discriminated between the sounds that they heard. By 10-12 months however, the infants no longer perceived the differences they detected a few months before. Thus, infants are born with the ability to discriminate between speech sounds in any language, but they gradually begin to specialise, retaining their sensitivity to sounds in their native language. Also demonstrates the use-it-or-lose-it phenomenon.